1. Field of the Invention
The present invention relates to a pattern forming method and an actinic-ray-sensitive or radiation-sensitive resin composition and a resist film used for the pattern forming method. More specifically, the present invention relates to a pattern forming method that is suitably used for a production process of a semiconductor such as IC, a production process of a circuit board of a liquid crystal, a thermal head, or the like, and other lithography processes of photofabrication, and relates to an actinic-ray-sensitive or radiation-sensitive resin composition and a resist film used for the pattern forming method. Particularly, the present invention relates to a pattern forming method that is suitably used for exposure performed by an ArF exposure apparatus and an ArF liquid immersion projection apparatus that use far-ultraviolet rays having a wavelength of 300 nm or less as a light source, and by an EUV exposure apparatus, and to an actinic-ray-sensitive or radiation-sensitive resin composition and a resist film used for the pattern forming method.
2. Description of the Related Art
Since a resist composition for a KrF excimer laser (248 nm) has been developed, a pattern forming method using chemical amplification has been used to compensate desensitization caused by the light absorption of the resist composition. For example, in positive type chemical amplification, first, a photoacid-generating agent that is included in an exposed portion in a resist composition is degraded by being irradiated with light and generates an acid. Thereafter, in a process such as PEB (Post Exposure Bake), by the catalytic action of the generated acid, an alkali-insoluble group included in the resist composition is changed to an alkali-soluble group. Subsequently, development is performed using, for example, an alkaline solution. In this manner, the exposed portion is removed, and a desired pattern is obtained (for example, see JP2009-235118A, JP2007-41146A, JP2009-237559A, and JP2000-159758).
In the above method, various alkaline developers have been suggested as the alkaline developer, and for example, an aqueous alkaline developer such as 2.38% by mass of aqueous TMAH (tetramethylammonium hydroxide) solution is widely used.
In order to miniaturize semiconductor elements, the wavelength of an exposure light source is being shortened, and a projection lens with a high numerical aperture (high NA) is being made. Currently, an exposure machine using an ArF excimer laser having a wavelength of 193 nm as a light source has been developed. As a technique for further improving resolving power, a method (that is, liquid immersion) of filling a liquid (also referred to as a “liquid for liquid immersion” hereinafter) having a high refractive index between a projection lens and a sample has been proposed. In addition, EUV lithography that performs exposure by using ultraviolet rays having a shorter wavelength (13.5 nm) has also been proposed.
However, in the current circumstances, it is very difficult to find out an appropriate combination of a resist composition, a developer, and a rinsing liquid, and the like, necessary for forming a pattern that has an excellent performance overall. Therefore, the further improvement of the performance is required.
In recent years, a pattern forming method that uses a developer containing an organic solvent has been undergoing development (for example, see JP2008-281975A, JP2010-139996A, JP2010-164958A, and JP2009-25707A). For example, JP2008-281975A discloses a pattern forming method that includes developing a resist composition that contains about 40 mol % of a repeating unit which has a group generating a polar group by being degraded by the action of an acid based on all repeating units in a resin and a repeating unit which has a norbornane lactone structure, by using a developer containing an organic solvent. JP2008-281975A discloses that according to this method, a fine pattern having small line width roughness (LWR) and high dimensional uniformity can be stably formed.
However, regarding the above-described composition, the LWR and exposure latitude (EL) are required to be further improved.